Despite optimal use of the several antiepileptic drugs marketed in the United States, many patients with epilepsy fail to experience seizure control and others do so only at the expense of significant toxic side effects. In the early 1970's, no convincing evidence had been published that the primary antiepileptic drugs marketed in the United States at that time controlled the seizures of more than 50% or improved more than 75% of the patients with epilepsy. The availability and use of several additional drugs since that time has brought improved seizure control to many patients. Notwithstanding the beneficial effects of the current drugs, there is still a need for new antiepileptic drugs with more selective anticonvulsant effects and less toxicity. E. A. Swinyard, et al., Epilepsia, 19, 409 (1978).